1. Field of Invention
This invention relates to control systems for kites, especially for, but not limited to traction kites used in the sport of kite surfing, snow kiting and other sports involving a person operating a kite as a means for propulsion.
2. Prior Art
Kite control systems for use with multi-line traction kites commonly consist of
(a) a center rope (8) which operatively connects a kite operator's harness (15) to the supporting flying lines (3) and (4) of a kite (1), which are connected to the leading edge (2) of the kite, and
(b) a movable control handlebar (11) which slides along the center rope, guided by a hole in the center of the bar. The left end of the bar is linked to a left control line (5), and the right end to a right control line (6). The control lines are attached either directly to the bar, or in an improved design linked indirectly through a pulley.
The handlebar is held by a human kite operator (14) with both hands and is used for a dual purpose: (a) to steer the kite to either side and (b) to adjust the angle of the kite relative to the wind in order to increase or decrease the lifting power generated by the kite, commonly referred to as powering or depowering the kite, or in sailing terms: “sheeting in” or “sheeting out” respectively.
To steer the kite, the control handlebar has to be pulled with one hand while releasing the other hand. To power or depower the kite, the handlebar needs to be either pulled or released with both hands simultaneously.
These actions require a significant amount of effort by the kite operator because part of the lifting power of the kite is distributed to the control lines. It is a common complaint among kite boarders that their arms and hands get prematurely tired when practicing their sport.
The french patent FR2762583 ‘Systeme de controle d'une aile ellipsoidal generalment en forme de fuseau spherique et retenue par des lignes’ describes a prior art system as illustrated above.
Another french patent FR2873093 ‘Dispositif de controle pour ailes de traction’ describes a 2:1 advantage steering system where each control line goes around a pulley (12a) and (12b) attached to each end of the handlebar. This recent development dramatically improves the maneuverability of the kite on the one hand, but on the other hand even increases the problems described above, due to an increased force on the handlebar. Some manufacturers therefore have abandoned the 2:1 steering system already.
Several attempts have been made to reduce the amount of effort necessary to control the kite. One such attempt is an extra harness loop (13) attached to the handlebar, which simply can be hooked to the harness and by doing so fixing the handlebar in place. The problem with this attempt is that it takes too long to unhook in case of a sudden need to depower, for instance because of a wind gust or a change in the moving direction of the kite operator, and thus looses its flexibility to adjust power.
Another attempt to solve the problem is by using a stopper ball (21) resting on a fixed member on the center rope. The stopper ball prevents the handlebar from sliding through the center rope, unless the force applied to the handlebar is beyond a certain amount. In order to depower, the handlebar has to be pushed forward vigorously which will push the stopper ball through. The disadvantages are: (a) only limited power adjustment is possible while the handlebar is resting on the stopper ball, (b) the stopper ball has to be reloaded manually, and (c) sometimes the stopper ball slides through unintendedly, and vice versa.
U.S. Pat. No. 6,514,115 ‘Line system for steering a kite’ teaches a different configuration of flying lines, using deflecting pulleys which link flying lines together. As a further ramification, it shows a pulley on the harness side of the control system, which has the purpose to take away the pulling force on the control handlebar. This solution unfortunately does not work on kite control systems which don't use the special line system described in said patent. If the full force of the supporting lines of the kite was redirected to the control handle bar, the kite would uncontrollably power up in a wind gust, and make the operation of the kite very unsafe.